Improvement in reciprocating steam-engines



ZSheets- -Shet. A. E. BAKER.

Reciprocating Steam-Engines.

No. 137,167, v PatentedMarch25,1873.

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Reciprocating Steam-Engines. No. 137,167. Patented March25, 1e73,

INVENTDR w/wf/wy AM. Pnora-umoaRAPH/c ca. MMJsBD/ms moons) UNITED STATESPATENT OFFICE.

AUGUSTUS E. BAKER, OF PROVIDENCE, RHODE ISLAND, ASSIGNOR TO HENRY W.GARDNER, OF SAME PLACE.

IMPROVEMENT IN RECIPROCATING STEAM-ENGINES.

Specification forming part of Letters Patent No. 137,167, dated' March25, 1873.

To all whom it may concern:

Be it known that I, AUGUSTUS E. BAKER, of the city and county ofProvidence, in the State of Rhode Island, have invented certain new anduseful Improvements in Steam-Engines; and I do hereby declare that thefollowing specification, taken in connection with the drawing making apart of the same, is a full, clear, and exact description thereof. Twosheets of drawing are presented, of which- Figure l is a side elevation.Fig. 2 isa longitudinal and vertical section through the cylinder,steam-chest, and exhaust-passages. Figs. 3, at, 5 show the constructionof the air dash-pot used to arrest the movement of the valves inclosing. Fig. 6 represents on an enlarged scale the cylinder inlongitudinal vertical section.

The improvements hereinafter described are particularly applicable to asteam-engineorganized on the plan shown in the Letters Patent granted toNoble T. Greene under date of March 13, 1855. In the machine of the saidGreene referred to the steam-valves are opened by means of tappet-smounted on a sliding bar, which latter is worked by an eccentric on themain shaft. Each tappet is in combination with an arm keyed to a shaftwith which the valve is linked, which arm, by the movement of the tappetas the sliding bar is worked, is vibrated through the arc of a circlesufficient to open the steanrport but the extent of movement of thetappet in a straight line is such that the face of the tappet and theface of the arm separate their contact, whereupon the valve is allowedto close by means of a weight or spring. To give a quick initialmovement to the steam-valves in closing by making use of asteam-pressure to assist this closing movement is one object of myinvention.

In the drawing, A represents the cylinder of the en gino, and'B thepiston. The two steamvalves are located at the ends of the cylinders inthe chests O O. In this instance the valves are of the variety known asgridiron slides, and are so set that their steam-ports are covered bythe movement of the respective valves in the direction toward theopposite end ofthe cylinder. The valves F are furnished with rods a,which pass through stuffing-boxes 6.

Their outer ends are slotted to receive tappets c, Fig. 2, which latterare keyed, respectively, to the transverse shafts d, upon the ends ofwhich are the arms c, Fig. 1, with which the tappets f on the slidingbar D engage for working the valves, substantially as shown anddescribed in the Letters Patent of the said Noble T. Greene, with thedifference that the valves in this instance, in closing, move in theopposite direction to that in which they are shown to move in the saidpatent.

In order to give a quick initial movement to the valve in closing I makethat part" of the valve-rods a which comes inside the steamchests of sogreat diameter as to cause a sea sible difference in the steam-pressureexerted upon the two ends of the valve. This excess of pressure appliedin the direction in which the valves move in closing causes the valvesto cover their ports upon the instant that they are released from thecontrol of the valve-gear.

It is well known that there is in all steamengines employing flatsliding valves and valve-rods passing through stuffing-boxes in thesteam-chest a greater degree of steampressure exerted upon the end ofsuch valves opposite to the end at which the valve-rod is connected, butsuch excess of pressure can be made practically useful for assisting theclosing movements of the valves only when a libcrating valve-gear isemployed, and under an arrangement which enables the valves in 010s ingto move in the direction of the stuffingboxes in the valve-chests.

A further improvement consists in the means employed for operating theexhaust-valves, whereby the valve at that end of the cylinder at whichthe steam is exhausting is permitted to remain wide open until thesteam-valve at that end is ready to open.

The two exhaust-valves g g, Fig. 2, located, respectively, at each endof the cylinder, are connected by the rod m midway between the endsthereof is a projecting lug, h. E is a twoarm wiper attached to a shaft,k, and which vibrates by means of an eccentric on the main shaft. Thelug it above mentioned stands in the space between the two arms of thewiper E, which arms radiate from the rocker-shaft k. The inner faceofone of these walls acts to throw the valve open at the proper time,and obviously the valve so opened will remain in the position in whichit was left until the arm h is acted upon by the inner face of the otherwall of the wiper to effect the return movement, and thus a freeexhaust-passage can be made to exist during the entire movement of thepiston for each stroke.

A further improvement resides in the arrangement for giving easy accessto the exhaust-valves.

At each end of the cylinder the clearances G G are made large, and theseconnect with a large exhaustchamber, H, made in the bed. From thischamber leads the exhaust-pipe 1. The cubical capacity of the chamber His intended to be as large as the cylinder. The exhaust valves g g andtheir seats are located at the entrance of the chamber H at each end,and at the bottom of the clearance-passages G G, as seen at Fig. 2, bywhich arrangement, upon removing the cylinder-heads, theexhkalust-valves and their seats are easily access- 1 e.

In this class of engines having liberating valve-gear and detachablevalves it is necessary to employ a means for arresting the movement ofthe steam-valves in closing. In Figs. 3 and 4 is shown the means forforming an air-cushion for this purpose commonly employed. I have,however, improved this device by combining with the weighted piston J ofthe air-cylinder a tapering plug, 7c, Fig.

5, which screws into the bottom of the piston,

and can be adjusted therein so as to contract earlier or later,relatively to the time of the closing of the valve, an orifice in thebottom of-the air-cylinder L, into which the conical portion of suchplug works, and thus regulate the arresting of the valves movement.

What I claim as my invention, and desire to secure by Letters Patent, is

1. The arrangement of the detachable sliding valves F F, theirvalve-rods a a, and the valve-gear which operates the valves for theiropening movements, substantially as herein described, whereby the excessof steam-pressure on the back ends of the valves may be made availableto assist their closing mox'ements, as herein set forth.

2. The combination of the two-arm wiper E on the rocker-shaft k, the twoexhaust'valves g g, and their connecting-rod m, substantially asdescribed.

3. The arrangement of the clearance-pas sages G G, the chamber H, theexhaust-valves y g, and the heads of the cylinder, substantial ly asdescribed.

4- The tapering adjustable plug K, in combination with the piston J andair-cylinder L, substantially as described.

AUGUSTUS E. BAKER.

Witnesses:

BENJ. F. THURSTON, EDWIN C. PIERCE.

